1. To continue the clinical follow-up and serial specimen collection on African Burkitt's lymphoma cases, both past and future. a. Clinical follow-up to include initial presenting features, relapse data by time and site and response to therapy. b. Specimens to include sera, tumor specimens when available, biopsies, assorted other specimens or tests as needed for special studies. 2. To complete a serial collection of clinical data and specimens (sera) from incident lymphoma cases for the analysis of HTLV-1. (Project partially completed). 3. To undertake a community survey and selected specialized surveys on particular subgroups, to-understand the epidemiology of retroviruses and HHV6.